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Finding the Fourth Proportional to 20.58, 30.81 and 12.55

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Solution

The fourth proportional to 20.58, 30.81 and 12.55 is: 18.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.58 : 30.81 = 12.55 : x
  2. Step 2: Convert to fraction form
    20.58/30.81 = 12.55/x
  3. Step 3: Cross multiply
    20.58x = 30.81 × 12.55
  4. Step 4: Simplify right side
    20.58x = 386.67
  5. Step 5: Solve for x
    x = 386.67/20.58
  6. Step 6: Final answer
    x = 18.79

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.